Heat exchanger



June 2, 1931. RL UHDE 1,808,619

HEAT EXCHANGER Filed Feb. 2o, 1929 Fig'. 1.

Patented June 2, 1931 s UNITED STATES PATENT OFFICE ROBERT UHDE, OFCASSEL-WILHELMSHOHE, GERMANY, ASSIGNOR TO S'CHMIDTSCHEHEISSDAMPF-GESELLSCHAFT MIT BESCHRNKTER HAFTUNG, OIEy CASSEL-WIL-HELIMSHOHE, GERMANY, A CORPORATION 0F GERMANY HEAT EXCHANGER Applicationled February 20, 1929, Serial No. 341,505, and in Germany March 8, 1928.

My invention relates to heat-exchangers and particularly to interstagesuperheaters with several groups of heatingtubes connected in series.

The construction of interstate superheaters for large powerinstallations presents considerable difficulties, principally on accountof the large dimensions necessitated by the volumes of steam to be dealtwith and of the considerable differences of' temperature to which theindividual parts of` the superheater are subjected.

In order to keep the dimensions of the superheater as small as possible,care must be taken to obtain an eilicient'transfer of heat from theheating steam to the interstage steam and to utilize as uniformly aspossible the space available within the superheater container. Theserequirements are fulfilled for example, by U-tubes connected to headers,if the groups of out-flow and return heating tubes are arranged insections or divisions, likewise in series, determined by partition wallswithin the superheater container, because in that case the interstagesteam to be superheated is maintained for its entire path in uniformcontact with the tubes carrying the heating steam.

In such an arrangement, however, very considerable differences oftemperature occur in the individual sections of the superheater. Thetemperature in the section receiving the interstage steam from theengine and receiving also the heating steam after it has already givenup a considerable part of its heat, preferably on the counterflowprinciple, is naturally considerably lower than in that section whichthe highlyheated interstage steam leaves and to which the heating steamis admitted at its highest temperature. y.

In order to avoid inadmissible` stresses in the heating-tube system andthe container walls, according to the present invention provision ismade for the individual parts subjected to unequal expansions to` movefreely in relation to one another. l

With this object,the heating tubes open into headers displaceable inrelation to one another, of which yonly one end header,

.pass to the condensate-eduction' pipe.

namely, the end header connected with the heating-steam outlet pipeorthe end header connected with the heating-steam inlet pipe, is fixed inrelation to the container, so that in consequence of the freedom of oneend of the heating tubes, no in-admissible stresses ycan occur in theintermediate headers through differential expansion of the groups oftubes.

It is already known in heat-exchange apparatus, to provide `a wall oftubes movable in a header, to which all the heating tubes are connectedat their ends. This construction, however, with large dimensionspresents considerable technical difficulties. In particular very heavystresses are produced in the tube system because groups of tubes of verydifferent' temperatures are connected to a common wall. l

It is also known to connect the tubes of heat-exchangers in groups toheaders movable in relation to one another. In this form-both endheaders are fastened to the container wall and in consequence cannotmove in relation thereto. This construction is therefore unsuitable forlarge interstage superheaters with very considerable differences oftemperature between the first and question, the heating steam has topass through a comparatively long serpentine course where it is in partcondensed by giving up heat to the medium to be heated,

while the condensate must-flow through successive tubes to the .endheader in Aorder izo n the parts of the tubes covered by condensate,heat transmission is, however, substantially less efficient than in thetubes 4containing no condensate, so that the condensate flowing throughthe tubes, in effect, renders a part vWalls of the heating tubes, sothat the arrangement according to the present invention leads to animprovement in the efliciency of working of the heat-exchanger.

In the accompanying drawings a form of the invention is shown by way ofexample. Y Figure 1 is a longitudinalsection; while Figure 2 shows to alarger scale, as rei gards itsleft-hand half a section on the brokenline II-II of Figure 2, and as regards its right-hand half a section onthe line III-III of Figure 1. The heat-exchanger shown comprises acylindrical container, 1, which is closed at one end by an end piece, 2,and at the other end by a readily removable cover, 3. An inletconnection, 4, is provided for the inv terstage steam to be heated andan outlet connection, 5, for the superheated interstage steam.

The heating-tube system lying in the container, l, consists of twogroups of U-tubes, 6, 7, and 8, 9, disposed in series. The outflowlengths, 6, of the first group of tubes are connected to a distributorheader, 10, while the vreturn leng'ths, 7 of this group deliver into anintermediate header, 11, from which the outflow -lengths of tube, 8, ofthe second group extend, the corresponding return lengths, 9, beingconnected to the end header, 12. f

Between the outflow and return groups of tubes, partitions, 13, 14 and15, are arranged in such a/way that U-shaped sections `orv divisions inseries are provided, through which the interstage steam flows on its wayfrom the inlet, 4, to the outlet, 5.

The partitions, 13, 14 and 15, in the form shown, are supported by angleirons, 16, which are fixed to the wall of the container, 1.

To the inlet header, 10, is connected the heating-steam inlet pipe, 18,which passes steam-tight through an aperture in the end,

2, ofthe container, this inlet pipe being expansion.; From the endheader, 12, leads curved within the container to provide for afheating-steam and condensate-eduction pipe,'19, which ylikewise passessteam-tight 'to'the outside of the container through an aperture inf-itsend,"2. The educton pipe,

19, forms a rigid connection between the i end header, 12, and the endof the container, 2, so that the heating tubes secured to this headermay be considered fixed in relation The tubes of the different groupsthrough-` out their length are inclined at a certain small angle to thehorizontal so that the condensate which forms in them can flow awayunder gravity.

Between the klower end of the intermediate header, 11, and theendheader, 12, a by-pass, 21, is provided throu h which condensate thathas formed in t e upper lengths of ktubes can iow direct from theheader, 11,

into the Aend header, 12. This by-passed condensate, therefore, in orderto pass to vthe condensate outlet need not flow through the lower groupof tubes lwhere it would exercise an unfavorable influence on theelficient transfer of heat. v

The correct relative position of the tubes 4is ensured in the usual wayby distance pieces and clamps, 22, which like the collector headers aresupported in a suitable manner on the lower part of the container wall.

As a heating-tube system is not fastened to the wall of the container,it can be readily withdrawn after disconnecting the pipes, 18 and 19,and removing the cover, 3.

The arrangement of the heating tubes and the manner of connecting themto the heating-steam inlet and outlet pipes can be modified withoutexceeding the scope of the invention. For example, the heating tubes canbe fastened to the heating-steam inlet and be freely movable in relationto the heating-steam outlet, the fixed connection `to the heating-steamoutlet being, however,

preferred on account of the lower temperature at that point. Inaddition, at the movable end, a straight pipe movable in a stuiing-boxcan be used instead of an expansion pipe for the connection of thelheating-steam pipe, the essential feature being that the kind ofconnection permits a straight-line movement of the end header at one endof the tubes in order to avoid dan gerous stresses on the tubes andespecially tilting of the intermediate header.

What I claim is:

1. In a heat exchanger the 'combination of a closed container providedwith an inlet connection and an outlet connection for the medium to beheated and with an inlet connection and Lan outlet connection for theheating medium, with afplurality of series connected groups of parallelconnected heating tubes disposed within said container, said groups ofheating tubes communicating with a plurality of headers movable withrespect to the container, one of the end headers being connected to theinlet and the other end header being connected to the outlet of theheating medium, one of said two end headers beingvfixed and the otherend header being freely movable in relation to the container.

2. A heat exchanger accordingV to claim l, the freely movable end headerbeing connected to one connection for the heating medium by an expansionpipe.

3. In a heat exchanger the combination of a closed container providedwith inlet connections and outlet connections for the medium to beheated and for the heating medium, the interior of the container beingdivided into sections formed by partitions' and arranged in series, withheating tubes disposed in the said sections of the container, saidheating tubes opening into relatively movable headers and being arrangedin series, one end header being connected to the inlet and the other endheader being connected to the outlet of the heating medium, one of saidtwo end headers being fixed and the other end header being freelymovable in4 relation to the container.

4. In av heat exchanger the combination of a closed container providedwith inlet and outlet connections for themedium to be heated and for theheating medium, with heating tubes disposed within -said contalner, saidtubes opening into headers and being arranged in series, the one endheader 4 vided with inlet and outlet connections for end' headers beingfixed and the other end header being the container.

6. A- heat exchanger comprising the combination of a closed containerprovided with inlet and outlet connections for the mediumJ to be heatedand with an inlet connection and an outlet connection for the heatingmedium, groups. of superposed freely movable. inrelation to `U-shapedheating tubes within the con'- tainer, the tubes'iof each group being soarranged that their planes are substantially parallel and the groupsbeing so arranged that the tubes of one group are in substantially thesame planes as the tubes of its adjacent group, said groups of tubesbeing connected in series -by superposed headers comprising two endheaders and at least one intermediate header, partitions between saidgroups of tubes and between the bends of each group, said partitionsbeing arranged to provide openings at alternate ends of the,A containerwhereby the container is divided into sections arranged in series, oneof the aforesaid end headers being connected to the inlet and the otherend header being connected to theoutlet of the Heating medium, one ofsaid end headers A,being fixed and the other being freelymovable inrelation to the container. 4.

In testimony whereof I` aiix my signature.

ROBERT UHDE.

